TWO-YEAR DIRECT AND INDIRECT COSTS FOR PATIENTS WITH INFLAMMATORY RHEUMATIC JOINT DISEASES: DATA FROM REAL LIFE FOLLOW-UP OF PATIENTS IN THE NOR-DMARD REGISTRY

Purpose: The overall aim of this study was to estimate total costs for patients with rheumatoid arthritis (RA), ankylosing spondylitis (AS) and psoriatic arthritis (PsA) in a cohort of patients treated with disease-modifying antirheumatic drugs (DMARDs). Specific aims were to compare costs across diagnoses and over time.

Method: The main data source was the Norwegian DMARD register (NOR-DMARD) that captures outcomes and resource use among patients starting therapy with synthetic and biologic DMARDs. Costs were estimated for four six-month periods from the start of a DMARD regimen. We included RA (n=1 664), AS (n=245) and PsA (n=491) patients with available 2-year data. Direct costs included pharmaceuticals, imaging examinations, stays in hospitals and rehabilitation units and visits to general practitioners, private rheumatologists, physiotherapists and outpatient clinics. Indirect cost included patients’ workforce participation. Differences in costs across diagnoses were tested by Kruskal-Wallis equality-of-populations rank test and changes in costs between first and fourth six-month period were tested by paired t-tests. 

Result: Total two-year costs were similar across diagnoses for patients on synthetic DMARD treatment (RA/AS/PsA $98 000/90 400/98 500) and on biologic DMARD treatment ($178 000/168 200/159 500). The largest cost component was productivity loss. Total costs decreased significantly from the first to the fourth 6-month period for all diagnoses, and this decrease was influenced by reductions both in direct and indirect costs. Mean total costs in US Dollar according to time period and diagnosis for patients treated with biologic DMARDs.

Diagnosis	Type of DMARD	Type of cost	Time period			p-value and 95%  CI for the change in cost between 1st and last 6-month period*
			0-6 months	6-12 months	12-24 months divided by 2
RA	Biologic n=489	Total	47 556	44 454	42 994	p<0.001 CI [2 964;3 974]
PsA	Biologic n=124	Total	44 869	38 459	38 110	p<0.001 CI [3 198;9 691]
AS	Biologic n=190	Total	46 320	41 613	40 111	p<0.001 CI [3 346;8 718]

*Paired T-test of no difference in costs between 1^st and last 6-months period

Conclusion: Total costs were similar across the main inflammatory rheumatic diseases. Biologic DMARD treatment entails considerable drug cost but the total costs decline during the first two years on treatment in both RA, AS and PsA.